scholarly journals Properties of Large Conductance Calcium-Activated Potassium Channels in Pyramidal Neurons from the Hippocampal CA1 Region of Adult Rats.

2001 ◽  
Vol 51 (6) ◽  
pp. 725-731 ◽  
Author(s):  
Liang-Wei Gong ◽  
Tian-Ming Gao ◽  
Hao Huang ◽  
Zhenqing Tong
Keyword(s):  
Potassium Channels ◽  
Pyramidal Neurons ◽  
Adult Rats ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Calcium Activated Potassium Channels

Kinetic properties of T-type Ca2+ currents in isolated rat hippocampal CA1 pyramidal neurons

1991 ◽  
Vol 65 (1) ◽  
pp. 148-155 ◽  
Author(s):  
K. Takahashi ◽  
S. Ueno ◽  
N. Akaike
Keyword(s):  
Pyramidal Neurons ◽  
External Solution ◽  
Kinetic Properties ◽  
Temperature Sensitive ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Current Voltage ◽  
Steady State Inactivation ◽  
The Individual

1. T-type Ca2+ channels producing a transient inward current were studied in pyramidal neurons acutely isolated from the ventral portion of rat hippocampal CA1 region. Membrane currents were recorded by the suction-pipette technique, which allows for internal perfusion under a single-electrode voltage clamp. 2. In all cells superfused with external solution containing 10 mM Ca2+, the T-type Ca2+ current was evoked by step depolarization to potentials more positive than -60 mV from a holding potential of -100 mV and reached a peak in the current-voltage relationship around -30 mV at 20–22 degrees C. 3. Activation and inactivation processes of T-type Ca2+ current were highly potential dependent, and the latter was fitted by a single exponential function. 4. Steady-state inactivation of T-type Ca2+ current could be fitted by a Boltzmann's equation with a slope factor of 6.0 and a half-inactivated voltage of -79 mV. 5. Recovery from inactivation of T-type Ca2+ current was not a single exponent. The major component of recovery (60-90% of total) was voltage sensitive with a time constant of 215 ms at -100 mV. 6. Amplitude of the T-type Ca2+ current depended on the external Ca2+ concentration. The ratio of peak amplitude in the individual current-voltage relationships of Ca2+, Ba2+, and Sr2+ currents passing through T-type Ca2+ channel was 1.0:0.85:1.32. The current kinetics were much the same. 7. All kinetic properties, including activation and inactivation, as well as the amplitude of T-type Ca2+ current, were temperature sensitive with Q10 (temperature coefficient) values of 1.7–;2.5.(ABSTRACT TRUNCATED AT 250 WORDS)

Modulatory effects of oligodendrocytes on the conduction velocity of action potentials along axons in the alveus of the rat hippocampal CA1 region

2007 ◽  
Vol 3 (4) ◽  
pp. 325-334 ◽  
Author(s):  
Yoshihiko Yamazaki ◽  
Yasukazu Hozumi ◽  
Kenya Kaneko ◽  
Toshimichi Sugihara ◽  
Satoshi Fujii ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Nmda Receptors ◽  
Conduction Velocity ◽  
Action Potentials ◽  
Pyramidal Neurons ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Inward Currents

AbstractLike neurons and astrocytes, oligodendrocytes have a variety of neurotransmitter receptors and ion channels. However, except for facilitating the rapid conduction of action potentials by forming myelin and buffering extracellular K+, little is known about the direct involvement of oligodendrocytes in neuronal activities. To investigate their physiological roles, we focused on oligodendrocytes in the alveus of the rat hippocampal CA1 region. These cells were found to respond to exogenously applied glutamate by depolarization through N-methyl-D-aspartate (NMDA) receptors and non-NMDA receptors. Electrical stimulation of the border between the alveus and stratum oriens evoked inward currents through several routes involving glutamate receptors and inward rectifier K+ channels. Moreover, electrical stimulation resembling in vivo activity evoked long-lasting depolarization. To examine the modulatory effects of oligodendrocytes on neuronal activities, we performed dual, whole-cell recording on CA1 pyramidal neurons and oligodendrocytes. Direct depolarization of oligodendrocytes shortened the latencies of action potentials evoked by antidromic stimulation. These results indicate that oligodendrocytes increase the conduction velocity of action potentials by a mechanism additional to saltatory conduction, and that they have active roles in information processing in the brain.

Somatostatin modulates high-voltage-activated Ca2+ channels in freshly dissociated rat hippocampal neurons

1995 ◽  
Vol 74 (3) ◽  
pp. 1028-1036 ◽  
Author(s):  
H. Ishibashi ◽  
N. Akaike
Keyword(s):  
High Voltage ◽  
Hippocampal Neurons ◽  
Pyramidal Neurons ◽  
Low Voltage ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Ca1 Region ◽  
Hippocampal Ca1 Region ◽  
Hippocampal Ca1 ◽  
Ca2 Channels

1. The effects of somatostatin (SS) on the low-voltage-activated and high-voltage-activated (HVA) Ca2+ channels in pyramidal neurons acutely dissociated from the hippocampal CA1 region of 2- to 3-wk-old rats were investigated in a nystatin perforated-patch recording configuration under voltage-clamp conditions. 2. SS had no effect on the low-voltage-activated Ca2+ channel but did inhibit the HVA Ca2+ channel in a concentration-, time-, and voltage-dependent manner. 3. SS showed the activation phase of Ba2+ current (IBa) passing through HVA Ca2+ channels, and the maximum inhibition was 28% of the total current amplitude measured 10 ms after the current activation. The inhibitory effect was eliminated by applying larger depolarizing prepulses. Pretreatment with pertussis toxin (PTX) completely blocked the effect of SS on HVA IBa, suggesting the contribution of PTX-sensitive Gi/Go proteins to the SS-induced inhibition. 4. The applications of forskolin, 8-Br-cAMP, dibutyryl-guanosine 3'5'-cyclic monophosphate, staurosporine, and 1-(5-isoquinolinylsulphonyl)-2-methylpiperazine did not affect either the control HVA IBa or the SS-induced inhibition of HVA IBa. 5. Pretreatment with protein kinase C (PKC) activators had no significant effect on HVA IBa but did remove the inhibition of HVA IBa by SS. 6. Omega-Conotoxin-GVIA, omega-agatoxin-IVA, nicardipine, and omega-conotoxin-MVIIC blocked HVA IBa by 27, 13, 38, and 9% of the total HVA current, respectively, which suggested the existence of N-, P-, L-, and Q-type HVA Ca2+ channels in the hippocampal CA1 pyramidal neurons.(ABSTRACT TRUNCATED AT 250 WORDS)

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